There has been plenty of speculation surrounding the Old Trafford future of the Spanish midfielder who was sold to United from Chelsea in January 2014.
While many think that Mourinho is not a fan of Mata, the Portuguese has again moved to suggest that indeed the 28-year-old has a part to play for the Red Devils in 2016/17.
"He's here and he works hard," Mourinho said in an interview with Sky Sports.
"He knows that I know he is a good player and he has space in the squad.
"Until August 31 the market is open for every one of my players that is not happy, but to be fair I think he is [happy].
"I think he is happy and I am not expecting him to ask to leave. I am expecting him to do what he is doing now, which is to fight for a place.
"In the end there will be space for everyone, we have 38 matches in the Premier League, we expect to play a lot of them in the Europa League and domestic cups so in a squad of, let's say, 22 players, there will be a space for everyone.
"So, yes, there is a space for Juan."